I think your proposed build is reasonable.
A balanced gamer will budget about 2x the cost of the processor for the graphics card.
You are spot on there.
ryzen is good for many cheap threads if rendering is most important to you.
Many threads are also good if you play multiplayer games with many participants.
For gaming, the excellent single thread performance is going to do perfectly well.
Gaming is usually more limited by the graphics card.
Do not worry about 9500 compatibility.
It requires bios 23 released on 7/26/2018. That is barely 3 weeks after the initial release of 22 on 7/3/2018.
Every motherboard will have a suitable bios to run.
If I have a suggestion it is to use a different ssd. The intel 660 is cheap, but I would use a Samsung 970 evo 1tb drive instead for better reliability and performance.
I would defer on the HDD if you need to for budget purposes. It is easy to add a HDD later when you need the room.
And... I think WD or hitachi might be a bit more reliable.
Here is a nice article on the WD options:
WD has a very diverse hard drive product line that can be difficult to decipher at times. In this article we go over the various 3.5inch hard drive lines from WD to help you decide which is right for your system.
www.pugetsystems.com