The tier list takes top level play into consideration. This wouldn't include you and your friends that don't play competitively.
Kirby has poor range, no mobility, is very light, isn't very fast in the air, can't camp, doesn't have any easy kill setups, has a deceptively bad recovery, a lot of his attacks can be SDI'd out of, half his grabs don't work, his frame data isn't particularly good...
*But*
If you do insist on being a Kirby main, Triple R is your guy to watch. His Kirby is extremely good. Kirby is very tiny, so he has a relatively small hurtbox, and can thus crouch under a lot of attacks that would otherwise hit most characters. His tilts and pokes aren't terrible, and Bair has a decent hitbox, and can kill/edgeguard decently well. Uair/Bair are good at gimping.
The trick is to sort of bait your opponent into over committing, with Kirby being difficult to hit and having jank, annoying moves. Then you sort of run away and repeat. Kirby isn't *that* bad at covering options off-stage, but he is slow compared to other common characters, so keep that in mind. Very hit-and-run. There isn't much you can do up-front, unless it's from a pseudo-tech-chase of sorts.
But yeah, watch Triple R.