The move powerful a character is, the harder it is to create situations when they can be either brave or cowardly.
A character who is almost totally omnipotent, almost totally invincible, and almost totally invulnerable, compared to the people and natural forces around him can not be either brave or cowardly. It is almost totally impossible for them to face danger, and thus almost totally impossible for them to be either brave or cowardly.
If heroism is defined as facing danger and what one is afraid of, then the more powerful the charcter, the less heroic they will be no matter what they do.
I have an idea for a character called Magnus the Great.
He is a highly eccentric and intelligent human hcild who basically is chose to become and immortal child. His bodie never grow old, and henever he may be killed he is given a new body.
He is sent to many different times and places in the universe.
When he visits a place as advanced as 21st century he can acquire smaell items which might be useful on his travels, such as, for example, a hand gun, a smart phone, a Swiss army knife, a pocketcalculator, etc.
And when he visits socities many thousands or millions of years more advanced, he sometimes acquires items which are of the same raltive importance in those societies, though many times more advanced than anything on present day Earth.
Picture the Krell machine in The Forbidden Planet (19560, a cube 20 miles on a side, able to read thoughts and provide whatever was desired. Suppose that if Krell society continued to advance, the dimensions of a newly built Krell machine might be reduced to only one half, and the volume to one eighth, every century.
After i century each side would be 10 miles long, after 2 centuries each side might be 5miles long, after three centuries each side might be 2.5 miles long, after four centuries 1.25 miles, after five centuries 0.625 miles or 3,30 feet, after 6 centuries 1,650 feet, after 7 centurie 825, after 8 centuries 412.5, after 9 centuries 206.25, and after 10 centuries 103.125 feet or 1,237.5 inches.
After another ten centuries the sides of a newly built Krell machine would 1.208496 inch long, and after another ten centuries, 3,000 years in all, each side of a newly built Krell Machine would be about 0.0011801 inch, almost microscopic.
So if Magnus obtains one or more pocket sized or dust sized equivalents of a Krell machine while visiting an advanced world, he would still be helpless against the most advanced technology of that world, but would have godlike power at his command compared to a technologically backwards society like 21st century Earth.
And you might remember the Star Trek episode "The Ultimate Computer" where the starship Enterprise is totally controlled by the M-5 computer.
Suppose that an advanced society has computer controlled starships as mighty as the Enterprise and 1,000 meters long, and advances fast enough that each century the dimensions of newly built computer controlled starships can be reduced by half.
After one thousand years the length of newly built computer controled starships would be reduced to 0.9765625 meters, after two thousand years to 0.0009536 meters or 0.9536 millimeters, almost microscopic.
So it would be possible for Magnus to acquire a fleet of tens, or maybe millions, of microscopic starships, controlled by computers which obey his mental commands, when visiting advanced societies, and so become as powerful as a Greek or Norse god compared to technologically primitive societies like 21st century Earth which he visits.
Mgnus is cautious and prudent and even cowardly, so when he has no advanced technology to protect him he behaves cautiously and advises those he may like to be be timid and cautious. And being intelligent, timid, and unemotional he spends a lot of time thinking about the best courses of action to take in various emergencies. So when those emergencies do happen, he takes the best course of action while not displaying much fear or other emotion, and so some people may falsely think that he is being brave insead of rational.
And when Magnus is equippped with tools, weapons, devices, and other stuff from societies many thousands or millions of years more advanced than the one he is in, he is almost totally omnipotent, almost totally invincible, and almost totally invulnerable compared to the people and natural forces around him. Thus it is almost totally impossible for him to face danger, and thus almost totally impossible for him to be either brave or cowardly.
So the greatness of Magnus the Great has nothing to do with his almost non esistent "heroism" but comes from other qualitiies he has.
There was another question asking about creating interesting stories about a very powerful character who can almost never be defeated conventionally.
Is there any point where an overpowered main character could be an interesting one?
Some answers, including mine, suggest ways to create interesting problems and situations for overpowered characters. They often involve the personal relationships or psychological hangups of the protagoists, or ethical dilemmas which can't be solved by their superpowers.
You should consider such suggestions. The less you want to use such suggestions, the less overpowered you should make your superhero protagonists.
You don't want to make a superhero too weak and too vulnerable. If he is not very powerful he will seem more heroic, but also more foolish the more he faces optimal dangers, instead of being forced by his conscience to protect the endangered. A character who rushes into danger thoughtlessly might seem like a thrill seeker with a psychological problem instead of a hero.
Thus while watching Duck Tales (2017) I more and more came to think that the MacDuck clan were all more or less insane, being totally irrational thrill seekers.
A veteran of the US Civil War reacted to being called a war hero by saying the real heroes of the war were dead. The greater the heroism the greater the probability of being killed performing that act of heroism. So surviving heros are likely to be less heroic on the average than dead heros were. The bravest men, and women, and children I have heard of almost all died as a result of their bravery.
But avoiding making a superhero too super is also a good idea.
The less super a superhero is compared to ordinary men, the greater the possibilities are to put them in real danger, and the more heroic they can seem. If they are invincible and invulnerable crimefighters, they might seem like a bully who get their kicks out of beating up helpless and defenseless criminals, using the crimes of criminals as an excuse to be brutal to them.
The tv series Dexter was about an evil serial killer who got his kicks out of identifying and killing other evil serial killers, and justified it to himself by claiming he was doing a public service by exterminating them.
A too invincible and too invulnerable superhero who always clobbers criminals and supervillains might seem to some readers or viewers like a somewhat less evil version of Dexter.
Which would be better than being a bully who gets their kicks out of beating up defenseless good people, but would still not be very heroic or admirable.
