the legs are backwards, rather literally. compare it with the loomis "ideal male" the entire character is blobby and fuzzy. lowpoly model, normal map, diffuse etc. it looks like you've used a 256² or even a 128² and scaled it waaay up. yes. it's important that you know how to work with normal maps, how to bake highpolies,…
If I were you, I'd drop the idea of doing highpolies and sculpting entirely for the next year at least. If you want to learn, start with lowpoly diffuse models (or 2D, whichever you prefer). I started off by doing 500 polygon tanks and although I never do vehicles anymore these days, I haven't regretted starting off with…