Hallo
If you can’t get Ubuntu-Mate or one of the other “lightweight” Ubuntus to run well have a try with “antiX” (https://distrowatch.com/table.php?distribution=antiX). I installed it last year on an IBM notebook (and I don’t mean Lenovo) that was bought in early 2005. The desktop is very simple but it runs well. If you need to get that hardware running and can’t upgrade the RAM this may help you.