Humans are very creative..but all thoughts must stem from some where. Perhaps the abstract is just a far fetched idea stemmed from a widely accepted one. If someone created a time machine and went back to 1810 a lot of our modern day life would be abstract to them. Like cell phones and other devices.
No, the abstract is not real as the definition of abstract is a thought that does not quite exist. it is an ojbect that one can imagine, or attempt to imagine, but not actually manifest. For example, one can think of a perfect cube, but that object cannot be manifested in to the real world.