Are these screws for bracket enough to support adult queen bed?
What is the diameter of the screws or size?  1-1/4" screws will have plenty of withdrawal strength and since there are 4 or 5 you really don’t need more than 3/4”. Wood screws that will fit the holes will provide plenty of strength. Since you have 1-1/4” those brackets will be stronger than the 2 pins they hang on.