If you get the "Introduction to Bach's Keyboard Music" by Palmer, you'll find a page with Bach's original instructions on how to play all ornaments but the easiest ones (e.g. the Schleifer/slide, I believe).
If you get Palmer's edition on the 2- and 3-part inventions, you will find a table with the speed that several editors suggest and several performers used. It's mindboggling! I believe there is an invention that Gould plays with MM=240 for the dotted quarter note, while Schiff is playing MM=80, or something like that. Since there are no metronome markings in Baroque, you can choose any speed you like!
There is a lot of info on the web. E.g., check out:
https://homepages.kdsi.net/~sherman/WTC.htmAnother thing: the inventions were written in a different tuning scheme. That's why there are only 15 inventions, not 24. To play all that correctly, you'd have to re-tune your piano, but it sounds fine as it is. Check out:
https://www.eunomios.org/contrib/francis1/francis1.htmlOf course, everyone nowadays uses dynamics with Bach. Some even argue that, because of that, one doesn't need all those ornaments anymore, because they were intended to draw attention to certain notes. On a piano, this can be done with dynamics, rendering ornaments obsolete.
Don't start a flame war now, please.