I do. If it were possible we'd surely see them everywhere. Even if time travel was a one-way trip there's enough future billions of us that there'd be massive numbers with the sort of incurable fascination seth the past that they'd be motivated to travel back and see what it was like.
Doesn't really seem any more or less likely than alien intelligence at any rate.
Time traveling humans is more likely for the following reason: It requires only one thing: worm hole or some other yet-to-be-invented mechanism for traveling to the past. For this to be alien intelligence, two things are required: First alien intelligence has to exist, and second, they too need a mechanism for speedy travel, to travel to another galaxy such that they can reach the destination within an individual alien's lifetime.
It has sophisticated filters and you can share reports with your team (as opposed to exporting CSVs).