Is there a reason I should backup all my files from old laptop when switching to a new one, or can I just install apps and re sign in to them

Hey all, so I'm getting a new laptop today to replace my old one and I have a question about the transfer. Should I back up everything from the old one or can I just download the apps I had to login to them?

The reason I ask is, I don't want a lot of these files. I got the computer in 2019 as a graduation present into my freshmen year of high-school so it's been almost 6 years. Highschool me downloaded a bunch of random nonsense for whim projects, a bunch of 2019 memes, and didn't Uninstall a lot of things completely right, I messed around with files, pirated movies, and just cluttered my laptop up with a bunch of nonsense files.

These machines both have a terabyte of storage and the old ones all filled up and I don't want to lose space to transferring my big chungus memes of old.

But everywhere I see it's recommended to back up the old pc and transfer all the data yknow the drill. I'm just worried that this new pc is gonna get cluttered up again from my demons of the pirating shows without a VPN days, because there is 6 years of stuff in the old pc

So is it a better idea for me to just not bother with transferring? Download all my old games and apps individually and log on manually to steam and disc and stuff so the ghosts of random files don't take a ride with everything else?

Thank you for reading my post ik it's long but I just like to provide full context for the situation. Any help is greatly appreciated!