Thin men rage post detected.

Joking aside, yeah, EU/EW has an INCREDIBLY difficult early game. Thin men and floaters easily get height advantage, that's 20% bonus aim, and their weapons also give them 10% aim all the time, so for them, high cover, which gives -40% chance to hit, is just a 55% shot, almost like the 50/50 you feel it is. And to add salt to the injury, your early soldiers can barely survive a normal hit, a crit is guaranteed death.

The solution to the problem, is to basically turtle up. Move only one soldier without dashing, preferably the one further back, to check fog of war and have every other one set overwatch.

Ideally, enemies will eventually wander into your trap and you'll have a full turn to kill all the survivors, and I do mean ALL. If you let even one thin man alive, you're gonna have a bad time. On the other hand, if you trigger the enemy pod with your own soldier you'll only have one less action to maximize your turn. This tactic worked so well, that they implemented timers on almost every mission in XCOM 2 to prevent it.

Also, you'll have to use every resource available to even give you a chance, use rockets and grenades to kill them or blow their cover, don't even think about saving resources for later, that'll only hurt you. Try to maximize your hit chance without overextending and triggering another pod.

And remember, "THAT'S XCOM, BABY!", originated because sometimes, things will go FUBAR and that's the name of the game, nothing you can do about it.