Welcome to the Forum and hopefully to Puerto Rico Macdonald3.
Jobs are hard to come by in PR unless you have a special skill that is needed in the island and that most Puerto Ricans do not study for. While the US is sitting at 4.5% unemployment, yet PR is at around 15% unemployment and getting worse. Being fluent in Spanish is a must for most jobs while some require good English. Very few jobs only require English. Here are some military bases where you may be likely to find jobs that require less Spanish: https://militarybases.com/puerto-rico/
Humacao is not expensive, Palmas del Mar is, but the prices have come down some and it sounds like what you need is a two bedroom condo or house (you should be able to get a 2-3 bedroom for about 500-700 a month fairly easily), however because you are only coming for a year or 3, I have to warn you that most rental units are just the walls, floor and ceiling. Most units have nothing inside, you have to get your own furniture, stove, refrigerator, washer, etc. Few units come equip in any way and they cost more. But not all is lost .... The owner may have some furniture and appliances that he may let you borrow or rent to you for a little more. But probably not enough to make you fully comfortable. I would suggest you get used stuff to lower the cost of getting new furniture.
I believe (could be wrong) that Palmas Academy in Humacao Palmas Del Mar community accepts kids from the surrounding area, if so you could live 3-15 minutes away and having inexpensive rent while still sending the kid there.
If you love scuba, boating and other water sports, just like Frogrock said, Fajardo is the gateway to the virgin Islands and lots of other tiny islands and associated reefs. Fajardo is 3 small towns away from Humacao and may be a bit much to drive from there to Palmas, so I would suggest Humacao and Naguabo as places to live. Humacao is more modern with lots of Supermarkets and banks and many things, while Naguabo does not have as many and it is more country. Naguabo does have many rivers with River pools, waterfalls and excellent places to eat fresh seafood. Seafood is everywhere in the island and in all costal towns obviously. By the way from Humacao to Fajardo it takes 15 minutes normally on PR53/PR3 (one is toll other is not, but they are basically different segments of the same road).
Rincon and surrounding areas also have a lot of English speakers and good schools, but I know little about them, other member here have already commented in the forum so the info is a search away, just search for schools, or bilingual, or kids. I can not tell you much about the west side of the island, my place and family are on and around the east coast.
So look at your budget for the adventure, you will need a car, a rental condo or house, appliances, furniture, plus utilities and deposits, then decide if this adventure is for you.