I think it is important to remember where these creatures came from. They are all religious in origin, and as such represent fundamental religious themes that have a corresponding resonance in the human heart (whether we actually believe the religious ideas or not, those ideas still resonate because they still address issues that have emotional and practical consequences for us, even if we accept other explanations for them).
While the modern high fantasy creatures come from Germanic and Norse mythology, similar figures with similar roles exist in many other cultures. They give form to our various fears and frailties, frailties which would have been much more immediate and in-your-face to preindustrial peoples with both fewer means to understand what was happening when things went wrong, and fewer means to resist the vagaries of chance or redress them.
Everyone who aspires to write fantasy, I believe, should know WB Yeats poem, The Stolen Child (https://www.poets.org/poetsorg/poem/stolen-child) which was used as the basis for a Loreena McKennitt song and a Doctor Who episode. It illustrates very clearly how the idea of faery folk expresses every parent's anxiety that they will lose a child.
Dragons represent our fear of the irresistibly destructive powers of nature: hurricane, forest fire, volcano. (They are also, in the Christian tradition, associated with Satan, the prince of lies.)
Elves represent the sense we get from the beauty of nature of an order in the universe more serene, more orderly, more beautiful, than our squalid lives. This can be associated both with great virtue and with great indifference, both of which are feelings we can get from a particularly beautiful scene. I remember standing at the top of a small rise in the middle of the Anza Borrego desert (a couple of hundred yards from the road; no wilderness trekker I) and feeling both how incredibly beautiful the scene before me was, and how implacably indifferent that environment was to my life or health. This enormously pure and exalted landscape would kill me with complete composure unshaded by regret or doubt.
Dwarves and orcs represent the powers and potentialities of the earth, the richness of its resources and the dangers it poses to anyone who explores it.
Witches represent our fears of disease and ill luck, misfortunes without any apparent cause or moral justification.
In short, all these creatures represent something elemental with an immense emotional punch for us, even in our relative comfort and safety today. (One could argue that our relative comfort and safety has actually made us more anxious than our ancestors, leading us to seek comfort in their old tales.)
You could, of course, invent new creatures to represent these elemental forces and fears, or borrow those of a different culture, but then you would have to work to do over of establishing their associations with our elementary hopes and fears. Using the standard pantheon gives you access to a set of built-in emotional responses which you can exploit to imbue your story with emotional resonance that would be hard to manufacture out of whole cloth.
Stories are made out of stories, they rely on the emotional potential of the base stories that people already know as a shorthand to evoking the basic emotional responses that you need to make your new story compelling. Making up your own mythology out of whole cloth may be an entertaining exercise for you, but it will come with none of the emotional charge of that the ancient myths come with.
There is nothing either boring or unoriginal about exploiting the emotionally charged images and stories that already populate your reader's imaginations. It is how the craft works, and the reason that every work of art lives and works within a broader artistic and cultural tradition.