If your concern is being put into potentially awkward groupings with others, my initial thought is that I believe that currently Disney is keeping groups separate on many rides. Also, I don't think any person should be concerned about how others react to them when solo. But apart from current distancing protocols and if it does concern you ....
First I think of the rides with single rider lines. There, everyone knows they might be grouped with a single rider because it is built into the riding system, and there should be no reason for anyone to look askance. I believe the single rider rides are Test Track, Rock and Roller Coaster, Everest, and Millenium Falcon Smugglers Run. Again, not sure if SR lines might be closed due to Covid. But when available to me they are a clear invitation to solo travelers.
Beyond that, and based on normal operating conditions:
- Kilimanjaro Safari is similar to Jungle Cruise. Big trucks, and everyone just piles in.
- Space Mountain has 3 person cars but nobody sits next to each other so everyone sort of is riding solo.
- In Tower of Terror Cast Members deftly mix and match parties in the 3 and 4 person rows so it is very common for people to sit next to someone they do not know.
- In Mission Space you'll end up in a tight pod with probably one other group/family, but without you they would have nobody to do one of the all important tasks and the mission would fail so win-win, right?
- In Soarin' everyone sits side by side but once the ride starts you basically feel like you're by yourself. Plus the rows are long so every party expects to have someone they don't know next to at least part of their group.
- Flight of Passage has all solo ride seats, and every group for the pre-ride experience usually has at least 2 parties anyway.
Also you should feel comfortable in all of the live shows, or movies (like Fantasmic), and things like the Tiki Room, where again, the rows are long and every group is next to some other person or group.
I'm sure there are others, but these came to mind right away for me.