An0n1m0u5e I would recommend you to read 'Everybody Loves Large Chests' first to see how other authors handle a monster mc and still keep it interesting.
Firstly, you shouldn't think like a human when writing your character. Your characters interests should align with it's nature. That doesn't mean it can't have it's own interests outside it's nature tho. Also, monsters or animals don't use human morals and values. It can learn what they are, but that still doesn't mean an animal would use them if it doesn't align with it's interests. Morals are just unnecessary constraints. So your character shouldn't be like a human turned animal if you wanna keep it interesting, it should be an animal that slowly gained sentience while still keeping it's instincts. Ofc, as your character grows it can learn from humans and even pretend, but that still doesn't mean it would want to follow their morals and values if it's constricting it's nature. Also some things that your character likes doesn't have to make sense from a humans point of view. For example, the mc of Everybody Loves Large Chests defines things it likes as 'tasty' while things it doesn't like as 'not tasty'. Shiny things are tasty, learning useful magic is also tasty, eating humans is really tasty! Getting stabbed is not tasty at all!!!
Warning, Everybody Loves Large Chests contains:
Gore, Profanity, Sexual Content(quite extreme)
Mc is not evil, but of chaotic allignment. After all, it is a monster. Also evil and good depends on the point of view of the one doing the judging. There is nothing wrong for a monster to massacre a village and eat everything to fill it's belly.