The mc isn't a human but isn't some cliche race like demon or elf or Dragon or just the common "I'm not human but I'm close enough and of course I'm amazing." Something out of the ordinary like mc is a snail or a beetle or a eagle or some sort of spirit or something.
How about slime? Vending machine? An egg? A spider? No idea how to link on my phone, but "Spirit Migration" have a spirit mc, and all the one listed above have a wn/ln, I just can't remember the name.
Spoiler: Swallowed Star Spoiler Swallowed Star... If you haven´t read it, you need to do it right now!. The MC was originally a human but after i don´t remember how many volumes he was forced to fight against a BABY golden horned beast but it was too powerful so the MC´s body ended up being destroyed and he was forced to take over the golden horned best´s body. The golden horned best is one of the most powerful best in Swallowed Star´s world and it´s more amaizing than a dragon or a phoenix
Mikayla the Dungeon (MC was human, transforms into a Dungeon core) The Rising (MC is / was the world's first AI) Pioneer 0 (MC is an AI / Robot (non humanoid), very likely abandoned by the author)
If you're looking for completely inhuman MC, I'd recommend those reincarnation novels where MC becomes either a sword or a vending machine. I Reincarnated Into a Vending Machine I Was a Sword When I Reincarnated
searching for salvation rrl mc reincarnates as caterpillar then evolves to a moth than final evolution is doxy a variant evil fairy... the kind that is not even a foot tall
Huh, guess I only have to input name for link to pop up. Here are the other I mention: Slime: "tensei shitara Slime Datta Ken", "Slime Tensei Monogatari", "Inside the Cave of Obscenity" Vending machine: "I Reincarnated Into a Vending Machine" Egg: "reincarnated as a dragon's egg" Spider: "Kumo Desu ga, Nani ka?"
http://www.novelupdates.com/stag/non-human-protagonist/ Some of them are humanoid, some aren't, but it generally becomes apparent quickly enough.
I liked that one but I kinda got annoyed by the constant "everything is in danger, I must save it all personally" crap that happens I dropped it at (iforgothowtospoilersoideletedit.) great novel until then, but I just got tired of the constant crap like that happening.
I reincarnated as a magic academy- he is reborn as a dungeon core but he gets a human form later which he always stays in EDIT: in his human form he installs lazers into his arms
An ultra cute dogee Woof Woof Story ~ I Told You a Rich Persons Dog, N... And not the villainous Albert daughter, but someone with the same name The Strongest Wingless Gargoyle