for basic function, everyone need 1g per kg bodyweight
for athletic training you need anywhere between 1.5-2.5 times that number
you dont "need" all of that protein to build muscle, but genetics governs how quickly you put on anyways
someone with ideal genetics could take in very little protein yet still build, whereas someone that may not have ideal genetics may need more protein intake
the numbers 1g per lb LBM is a fairly accurate number BUT most people dont know their LBM
so to be safe shooting for 1g per lb of bodyweight is pretty safe...it definitely doesnt hurt.