What do you think of my build? Do you think I should upgrade? If so, what should I upgrade first?
I would say upgrade your video card. Most games don't take advantage of more cores (that is changing). If you look into used cards you can probably get a decent upgrade for about what you paid for your original card. I got a used 1070 in my system for $237 about 2 years ago. 1660 super is also a good choice.
If you do upgrade your CPU a 3600 will be a nice bump and serve you well for a few years.
thanks, so which should I upgrade first, the CPU to a 3600, or the GPU to the 1660?
3600, then a 1660S. or whatever is the X60 GPU then.
I'd go with the GPU first. That will have the bigger gains in game. What one to get depends on your budget. Once you know your price, pick a few models, and watch some reviews to help you pick the best one. Hardware Unboxed and Gamers Nexus tend to do very thorough reviews.