Yes in many parts of the US it's not just the heat but the humidity. One summer I tried going without AC as much as possible to see how much it would change my electric bill. I could handle the temperature most of the time but the humidity especially at night started giving me mold problems in the house. Cleaned that up and went back to using the AC and no more mold. Not sure how people controlled this back in the pre-AC days, maybe just a lot more cleaning.

My parents still don’t use AC. The windows stay open all summer unless there is a rainstorm. Whole house fan is turned on at night to draw in cooler air. Much time spent in the cooler basement if you are going to be hanging at home. At night you are basically sleeping naked on top of your fitted sheet with one or two window unit fans circulating air. Maybe another fan pointed directly at you. Basement had some dehumidifiers and afaik that was the only problem moisture area.

If you are OK with the heat maybe a dehumidifier would be able to address the humidity problem while still saving electricity compare to the AC.