Your GPA and MCAT is pretty good, you come from a top 10 undergrad and you're a history major with research in another discipline. It sounds like life happened and for whatever reason getting involved in science research just didn't pan out for you. I wouldn't worry too much - I would definitely get a bunch of clinical experience in lieu of the lack of science research. Maybe someone who knows more than I can chime in.
You don't need research for low/mid tier schools. The MSAR research statistics are exaggerated because many applicants usually list dishwashing and maintenance duties as research rather than solid, independent, hypothesis-driven project.
Independent study doesn't fit the formal research requirement since it sounds like you did a class project on your own initiative (which is fine and a good topic to discuss in interviews). The research at a museum exhibit may be considered to be one, but it really doesn't appear to be hypothesis-driven at first glance .
But keep these activities in your W&A. Your stats and Top 10 background will make your application cycle fruitful. Good luck
I hope this would help. From AAMC's official guide to the MCAT exam, it says research is not important for public schools. And it is not as important as health care experience or volunteer experience for private schools. Please see the table I attached below.