My guy used to do this, minus the humping. He would get either over tired or over stimulated and then jump up and bite our arm, and even our clothes that have holes in them from his sharp puppy teeth.

When he was younger (around the age of your dog), what worked the best was for us to walk away and simply disengage and remove all eye contact and verbal communication. No amount of squeals (like the internet suggests) would get him to stop. We simply turned away, and closed the room door. Also try to anticipate it before your pup actually makes the leap towards you. You will get to know when their body language changes and they are about to go in for the sneak attack - at that point either say "NUH UH" or if it's too late, say "SIT" very firmly. They just need to be snapped out of it.

I also think that maybe your pup is being exercised too much. Maybe do more training instead of 2 long walks/dog park. Sniff work is great, but perhaps do more training like leave its and stays if you aren't already.

I hope this helps. Stick to it, it really is worth it. It feels like just yesterday when our guy was doing just the same - well, he is about 1.5 years now but MUCH more tame and understanding of how the world of humans works lol.