My JRT sausage dog mix possessiveness over toys Questions

Hello everyone,
I didn’t figure how to introduce myself elsewhere so I will do it here(apologies if it isn’t the right place).
I am Elena and I own a Jack Russell-Terrier/Dachshund mix who is absolutely lovely and extremely intelligent, very well trained and behaved, neutered but there is a small BUT- he is very possessive of his toys, he takes fluffy dogs as his toys such as cockapoos(maybe due to their kind and submissive nature) and he will occasionally attack other dogs when they attempt to take his ball or try to hump his fluffy friends. Most of the times I get him to walk out of the situation and calm down but on the odd occasion he attacks the dogs and I am trying to correct this but it’s working for a little while and then he goes back to it. Could you please give me some advice? Attaching photo of little Simba )
Thank you.

I don't understand, 'he takes fluffy dogs as his toys'. Does this mean that he will play nicely with gentle submissive dogs, but is aggressive when others want to join in? Is this in a dog park situation?
I would avoid letting him get into situations where each dog present is not under the control of its owner. By all means let him play with a dog that he gets on well with, that is good for developing his social skills, but allowing rough and unfamiliar dogs to join in the game is bound to lead to trouble.
You say he is possessive with his toys. Is this also in the playground situation, or at home?
If his toys are getting 'stolen' in the play area, you are better avoiding stimulating games like throwing balls, which are competitive and tempt the others to pile in. Save these games for quieter areas. If he is being possessive with you when you need to take something away from him, teach him at home to exchange a treasured item for a treat. Turn swapping items into a game, and reward with gentle praise and a tasty treat for doing it nicely.

Thank you for your response. He plays nicely with all dogs in the park until there is a toy of his involved or another dog he is getting along well with and another dog comes and tries to join in.
He is protective over his toys at home and in the park, not aggressive or snappy towards me- never or to other humans, just dogs who try to steal his toy or join a play with a dog he is already engaged in a okay with. I guess I will just need to avoid those places or situations, there is no way around it.

If he is only aggressive when another dog take his toy, I really wouldn't be putting him in a situation where it can happen,

Think about it on a different level. You have a favourite piece of, say, jewellery and someone comes along and takes it away from you. Would you be friendly towards them?

I would suggest not taking any of his toys with you when you go to the dog park.

Thank you. I think you’re all correct.

I will try not taking any toys to the park and see how he behaves. I normally don’t allow other dog owners give him treats outside as he doesn’t share food either and that’s working well.

What I was getting worried about is that his behavior is abnormal although I know it isn’t but it’s good to have some reassurance from fellow owners.

Thank you.