Why is it "nowi" for chłopcy and "nowe" for buty? A bit confused as theyre both masculine nouns. Something about being animate?
Exaclty, animate masculine plural = e.g. nowi, starzy
Any other plural (neuter, feminine, inanimate masculine) = e.g. nowe, stare
Could someone please explain to me why 'chłopcy' takes the adjective 'nowi' and not 'nowy'?
'Nowi' is for plural, while 'nowy' is singular (both forms masculine-personal).
Unfortunately the endings don't match with the noun, and i think that is what mislead you.
Nominative masculine personal plural adjectives have a consonant shift (in this case, w to w(i)).
I wrote a bit about consonant shifts, including in adjectives, here: https://www.duolingo.com/comment/12262354
What case is "nowe buty" in?