Why my brother who is 23 years old cannot petition for my father because it would take longer?

Generally a U.S. citizen age 21 or older may sponsor a parent for attaining immigration benefits through an adjustment of status process if the parent is in the U.S., or through consular processing if the parent is outside of the U.S. There are, of course, many details that determine eligibility. There really is no substitute for your brother and your father to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.