There shouldn't be a big problem creating male characters. People are people, whether they are male humans, female humans, children, thousand-year-old vampires, thousand-year-old child vampires, tentacled aliens, intelligent machines, gods, or whatever.
When you look at a group from the outside they might all seem identical, but if you study the biographies of individual members of the group you begin to see major or minor differences and individual traits.
For example, farmers, pet owners, zookeepers, animal trainers, etc. who get to know several animals of a species will come to see what they have in common and also see that each and every one that they know has specific individual personality traits.
You should look up pictures or videos of feeding Gomek, a giant salt water crocodile, at the St. Augustine Alligator Farm. Gomek was so incredibly tame - for a crocodile, that is - that his keepers actually dared to get inside his enclosure and feed him from a distance of only a few feet, creating extremely frightening photos. Don't try that with any other large crocodile!!
Humans and other intelligent beings have highly complex intellectual and emotional lives, and thus have hundreds and thousands of personality aspects that they can have varying degrees of, and thus have much more varied personalities than ordinary animals.
Since military leaders were mentioned in the original question, here are some military leaders.
Field Marshall Wilhelm Keitel (1882-1946) Chief of Armed Forces High Command in WWII, hanged for war crimes, was described by allied interrogators as a typical Prussian Junker, but his family wan't Prussian. Keitel's father was a citizen of the Kingdom of Hanover when it was conquered by Prussia in 1866, and moved to the Duchy of Brunswick, ruled by another branch of the House of Guelf, in protest of the conquest.
Field Marshal Paul Ludwig Ewald von Kleist (1881-1954) was tried for war crimes in the USSR. But one very strange thing I have read is that the changes included seducing Soviet citizens from their allegiance by too humane treatment of them. I don't know if those were actual charges, but if true that would be an unusual characterization of a Nazi general, to say nothing of characterizing Stalin.
In the US Indian Wars General Alfred Sully (1820-1879) commanded in some of the largest battles and his forces killed, wounded, captured, and otherwise defeated hundreds of Sioux warriors, making him one of the most successful Indian fighting generals. Sully also married a French-Sioux half breed and had a daughter Mary Sully who married a Sioux Christian minister and became the ancestor of Vine Deloria Jr. (1933-2005), a Sioux activist and author of Custer Died For Your Sins. Alfred Sully was a son of painter Thomas Sully (1783-1872) and was a talented artist himself - his paintings include depictions of two of his battles.
Ranald Slidell Mackenzie (1840-1889) was one of the best generals in the Civil War and the Indian Wars, but was quite eccentric. He was eventually retired in 1884 for insanity.
General George Crook (1828-1890) was also very eccentric. His forces probably killed, wounded, captured, and otherwise defeated more Indians than those of any other US general of his time, and he personally allegedly shot nine Indian warriors. But he was also noted for his ability to understand and manage Indians and was an advocate for Indian rights.
And here is a sort of gender related observation.
You may or may not know that the ideology of the Holy Roman Empire was that the Emperors back to Charlemagne (crowned in AD 800) were the rightful successors of Constantine VI who was deposed by his mother Irene in 797, and of the eastern Roman or "Byzantine" emperors back to Arcadius (r. 395-408), and of the Roman emperors back to the first, Augustus (r. 27 BC- AD 14).
Francis II & I abdicated as Emperor of the Romans in 1806, and his present heir according to the dynastic rules of the House of Habsburg-Lorraine is Karl von Habsburg (b. 1961) whose only son and heir is Ferdinand Zvonomir von Habsburg (born 21 June 1997), who has a career as a racer. Ferdinand Zvonomir von Habsburg can claim to be the heir to the Holy Roman, "Byzantine", and Roman Emperors.
And the Roman Emperors include Varius Avitus Bassianus (c.204-222), who usurped the throne in a bloody civil war in 218 and used the throne name of Marcus Aurelius Antoninus Augustus, but is better known as Elagabalus. According to Roman historians Elagabalus was extremely effeminate, the sissiest sissy ever. Despite the fact that his hobbies included chariot driving, more or less the third century equivalent of Ferdinand Zvonomir von Habsburg's auto racing.
So the thought has occurred to me that if someone writes a story where Elagabalus is actually a girl in disguise - thus explaining their effeminate behavior - the chariot driving scenes would make them seem like a partial tomboy.
In any case the stories about Elagabalus mix rather macho behavior like chariot driving with feminine behavior, thus indicating that Elagabalus might have had a complex and mixed personality.
And the point of the story about Elagabalus may be that people do what they want or feel overpowering urges to do, and in many cases apparently without worrying about how their actions fit in with gender norms or stereotypes.
And it seems to me that the more often a character appears in a story, the more different situations they will appear in, and the more opportunities there will be to reveal individual personality traits.