I'd recommend Zorin lite with these specs. You can try Zorin Core with a USB Zorin Boot Stick and when it runs well stay at it. But probably Zorin lite will run smoother, especially when you want to use it for watching videos. Zorin 18 lite has not yet been releases, but you could try Zorin 17 lite.
I would second the recommendation for Zorin Lite. While you may get away with Core, Lite would allow your system most likely to run much more smoothly for the level of hardware we're seeing here.
You could try Core and see how it runs for apps that you are likely to use. If you can throw some more RAM at that machine it would help.
Note Z18Lite is not yet available and the devs will not create a Lite edition beyond Z18 if you were thinking much longer term.
Whilst live mode (Try Zorin) will be slower than an install at least you could get some idea as to how it would fare. I would also consider a couple of other options such as Linux Mint Debian Edition and Q4OS Plasma and test those in live mode too to compare how faster or slower they are than Zorin 18 in live mode.