Is my cat getting old?

My cat is 5.5 yo and I’ve got him for 6 months. Before moving in with me he was shaved because they were all matted and tangled up. Now that they are growing back there is white hair under his belly. Is this normal or is he getting old? Before the shave he was an all black cat.

I believe he’s not a smoke color cat since his root is black/brown and the tip is white (whereas in smoke color cat it’s the reverse).

First 2 photos are him now. Third photo is him at around 2 yo.