Whenever I visit Bangkok, which used to be about once a year, I found the local people's English level to be good enough to have basic conversations, share a laugh, and somehow connect with people in a meaningful way.
At a print shop, the owner chatted me up about Trump. That was back when he first got elected. He could articulate his political views about US foreign policy and international relations, in that charming Thai accent.
One of the ways Thai people seem to all know a little English is they seem generally curious, and social. They smile and chat with tourists in a genuine way that I haven't often seen in other Asian countries.
There are those who think the much-loved "Thai smile" has sinister motives behind it. What they could be is beyond me. The waitress at the Chilis by my house in Florida also smiles. Is it because she just wants my money? Perhaps but I'm ok with that!
Outside of Bangkok, the English levels vary immensely. If I find myself in a remote village on a stop to the next beach town, local people are generally unable to communicate in English. So then It's time to turn on my bad Thai.
One of the joys of visiting Thailand, beyond the food, the beaches, the culture, the weather, and the cheap everything, is the local people's willingness to connect with tourists in English.