Can there be other life on other planets, and did Allah send them messengers, books, and a religion of their own other than Islam? And are these ideas considered disbelief?

One should direct their effort to inquiring about the fundamentals of faith, the actions of the heart, and acts of worship. The Companions' approach with the Messenger of Allah, peace be upon him, was that they would ask him about matters of actual occurrences that would benefit them, not hypothetical scenarios or complex, intractable issues. Many of the Companions and their successors (Tabi'un) disliked asking about events before they happened. Contemplating the aforementioned question is not disbelief. Asking about strange and hypothetical matters is reprehensible in Islamic law; the Imams disliked it and forbade it. 'Umar, may Allah be pleased with him, used to curse whoever asked about what had not yet occurred. Zayd ibn Thabit and 'Ammar ibn Yasir would not discuss what had not happened, waiting for its occurrence. Sayings and actions have been reported from the early generations (Salaf) indicating their dislike for this type of question, considering it among the issues of deviant people.