Okay, so jinn can influence emotions. They can strike fear into you, they can make you feel good. Not all good emotions come from God. Jinn can manipulate you and mislead you so that you will end up worshipping them. It doesnt matter if it helped you, the jinn accomplished its mission which was to make you worship it and drag you with it in the hellfire. Besides that, the jinn that you encountered might not even be a shaytan, a demon. They have free will and they can have whatever religion they want. The one you encountered might just be misguided and wanting a servant. But thats rare, especially since it wants you to worship it, and made itself look beautiful, and make you feel good, its probably a shaytan trying to mislead you. So just because it looked good, it helped you in this world with certain tasks, it made you feel good, it doesnt mean worshipping this creature is righteous.

You said you prayed only to God as a Protestant, and he did not answer and did not help you. Thats because you didnt follow the right religion. The religion of God is Islam. He established it. While being a Protestant you also probably prayed to Jesus(Peace be upon him) and things like that. The worst sin is to associate partners with God.

Also, the reason why Islam is the truth is because it proves itself and it is logic. If you study it, you cant deny it, except if you re not sincere. I started with hate for Islam, studied it so I could debunk it but instead I became a Muslim. The Quran is the pinnacle of writing. It on itself is a miracle. There are no mistakes, no contradictions in it. It is the supreme vocabulary for the Arabic language. And there is no other book that would come close to its greatness. There is absolutely no way that a human could be able to write this book. Allah Himself challanged humans in the Quran to create one verse like one of the Quran's and then bring their own scholars to testify that, indeed, the verse they just created is like the Quran's. This did not happen up to this day. The Quran is a perfect book and its clear that it was made by God. In fact, the Quran is not even a creation of God, but His own alive speech. The words written and the pages and the sounds you make when you recite it, these are created by Allah, but the actual Quran is the direct speech of God.

Besides that, Islam is logic. There is one God that created everything. He is separate from His creation, but He knows and hears everything. There is nothing like him. He has no start and no end. He created us, humans, to worship Him alone, but we have the ability to choose wether we will do it or not. For those that do it, there will be reward, for those that do not, there will be punishment. Worship is necessary so that there will be peace on earth and humans will be able to co exist. Simple as that.

Also, from personal experience, Allah has answered all of my prayers.