I have seen several tourist couples with their baby in San Pedro, but did note each had grand parents with them, to help with the baby, especially when the couple wanted to do tours.
I am sure the Coconut beach is safe. But I would watch the baby closely. Remember the dogs walk the beach too, and leave behind feces. Wash your baby really good when leaving the beach.
If your baby has a sensitive system, may not be the best vacation place. Remember new foods and water. Also the sun is intense, must use alot of protection.
Jungle......personally I would not take a baby to the jungle area, but I am a preventive person, not a risk taker with babies.
Best wishes on your vacation.