The UI usually maps linear motion quite naturally. In real use the control is mapped to a physical knob via MIDI, if you'll be tweaking it on the fly.

I wanted to learn Ableton and have determined that it,s futile unless I get a MIDI controller

Absolutely untrue, but a MIDI keyboard will certainly improve the experience.

I hope you see this, just noticed your reply! Thanks for the encouragement, music production/DJing is something I really want to get into, so encouragement is extremely welcome. :) My problem when I tried using it was that the knobs were really difficult to adjust with my mouse, like it didn’t feel responsive. Am I doing something wrong?

No. There are so many plugins and so many knobs that you will never have enough MIDI control panels and time to set them up.