Based on the stills, there's nothing unusual here.
The tapes suffer from your usual homeshot video problems: grain, off-white balance, mixed-temp color casting, color unsaturated (on some, not all). But those are mostly camera/shooting issues, nothing to do with age. Grain is a tape quality issue, and was there when the image was recorded.
Your tapes look like mine, and most others.
The true test is viewing clips. Lots of errors are invisible on stills, but obvious in motion.
Hi8 looks better than VHS, and tends to have less issues. So you have that going for you.