Their intentions was for the congress to have power and to make decisions, while the president would be an executive figure that would organize the execution of the congress decisions. This changed overtime as presidents found ways to get more power which were sometimes implied in the constitution or were not even mentioned but weren't forbidden.
They believed that the legislative branch should dominate the federal government since the executive power was weak and was prone to change through things like elections and would divide people and similar things. They believe that the president should only serve to execute the plans that the congress passed.