The Democrats did not win this election. They were just there when the Republicans lost it. I've already heard Democrat commentators say that they'll win in 2028 if they get nothing done over the next two years because Trump veto'd everything. They said this as if it was a good thing!
Don't count on it. The U.S. has started a lot of fires around the world in the last two years. Some are burning strongly enough that, if the U.S. doesn't put them out promptly, somebody else or some group of nations will. An American's first reaction might be, "Won't it be great if somebody does the U.S.'s job for a change?" Being the benevolent "Global hegemon" was the U.S.'s job. If you're not doing the job, you're no longer it. If somebody else starts doing that job, the U.S. will just be another misbehaving middle power with an overly expensive military and no soft power. Trump has shown what relying completely on hard power and neglecting soft power can accomplish.
Having the Democrats in control of Congress is a step forward, but it's just a tiny first step. Americans, don't let your leaders play at politics for two years while the fires keep burning. Congratulate your new representatives, but don't let them believe they won this election. They were just there when the Republicans lost it. Their task is to keep the job, if they can.