Perhaps the teachers didn't recognize you (did you have a mask on) or just didn't want to stop and chat- I've found often my children's teachers don't seem to know me out of the school context, whereas if I'm with one of the children, they will usually say hi.
I think you are telling yourself a story that appears plausible, but you could easily tell yourself a different one. I have never been popular at school, or at the school gate when my children grew up, just not a big group person, so I tend to find that one other mum on their own and chat to them, and I have work colleagues I get on with really well.
Your friends might be struggling a bit to know what to say about the cancer, perhaps you could take the lead by texting them a bit to let them know how you are getting on. In an ideal world, they would check in without asking frequently, in the real world, having gone through a traumatic time, I noticed although some people did do that, often others did not. I am able to accept that not everyone has the same to give at all times- so if there's one person who texts, take that as a win. Do you text them a lot to find out how they are- it's been a very stressful time for everyone lately? I always wanted to be a good friend to others even when I had my own troubles and I think that pays off.
What I mean is- most people could gather evidence of being 'unlikeable' in some form or another, someone not looking at them/running away in the street, friends not always texting, feeling left out of the big mum group- but that's often not the whole truth of what's happening. These types of things happen to everyone, and it's whether you ruminate on them and kind of make them worse, or whether you look for the positives in your work colleagues/friendships that makes a big difference.