That's it.
Slow down.
I have given this advice to multiple people who were new to bike commuting and every single one looked at me like I was a Martian. A week later they said "You were right!"
I've biked in one hundred degree weather and arrived in barely a light sweat. Yes, I put on hiking shorts which were passable, and the lightest athletic shirt I owned, but I didn't need a shower.
I just budgeted a bunch of extra time that morning, and barely pressed the pedals, whereas usually I'd be pedaling decently hard the entire way, even down hills. Because I was expending virtually no effort - biking is more efficient than walking - and had a ~10mph breeze - I was comfortable.
It helps that I eat a decently varied diet so I don't have horrific BO, use soaps that aren't loaded with shitty artificial scents and chemicals, and wash my clothing with no softener and "free" detergent that lacks any sort of perfume.
Most people sweat just standing in 100 degree weather, so maybe you are unusual?
As a non-ebike rider I admit my lack of peripheral vision (age) is making the zoom! of an ebike or scooter past me increasingly scary, but the fact is, my declining vision is more of the issue than the ebike is.
E-bikes should take over in most cities. All but the most disabled can ride them. Cities like Taipei and Barcelona that already move on scooters would get much cleaner air and have the same low-cost mobility. New York makes no damn sense for cars. Even large spread-out cities are easily traversed on e-bikes. Assholes on e-bikes can be annoying but rarely deadly. Drivers who kill cyclists should be imprisoned until too old to drive again. Cars should all be required to have passive braking that won't come within 6 feet of a cyclist or pedestrian. regarding pedestrians, we could start by recognizing that "jaywalking" isn't a thing.
Yes, like all things, there are jerks who will ruin it for everyone else, which is unfortunate when it seems to be a net benefit.
There is a ton of <X> hate in the <Y> world. Cars, bikes, iPhones, Androids, dogs, cats, you name it, everything is a team sport you have to win.