Biggest impact on low performance of your Mac is the mechanical hard drive.
Only 4GB of RAM is also too low. Etrecheck read only 20MB available at the check. It is good to use as much RAM as possible, but it sometimes means that's just not enough. And 4GB are not enough.
Catalina is a pretty modern OS and it handles a big amount of data, so an SSD and 8GB of RAM are kinda basic for acceptable performance.
Etrecheck also reported some other things that can cause trouble:
- Old and orphan files that are probably remains from older OS and apps versions after updates
- 2 antivirus apps detected, they can mess with each other and with macOS
- 32-bit apps that are not supported in Catalina still installed.
Best thing to do is to replace the HDD with an SSD and make a fresh install of Catalina. Be aware that this model sometimes shows a problem in the flat cable when the HDD is replaced, so you might end up having to replace the cable too.
If possible, change the RAM to at least 8GB.