Selection bias means that because math and humanities majors have not coursework that overlaps with pre-med requirements, those math and humanities majors who do apply to medical school a make an proactive decision to do so and go out of their way to make sure they have all the necessary components for a very strong application.
Those numbers are from the most recent application cycle (2020-2021). You can see the numbers here: https://www.aamc.org/media/6061/download?attachment
No, a math major wouldn’t look funny at all…Both of my daughters had a math major and they are both now physicians. Not single individual ever commented on their choice of major. (Well, except for that one creep who was either very seriously sexist or very socially awkward who told D1 she was “way too pretty to have been a physics major” and that “if [his] physics teacher had been as pretty as she was, [he]'d have a lot paid more attention in class”.) Why would an adcomm member look askance at math major applying to med school? How would that be any different than a Spanish major, or a dance major or computer science major who applies to med school?
And remember the adcomm member interviewing you may have earned a degree in electrical engineering or music or history before they went to med school–you just don’t know.
Adcomms really do not care at all what your major is. They are just looking for smart people who have demonstrated they can be academically successful at very high level and who have the personal qualities that make a good physician.