Do you really think that the elongated interstellar object zooming through space, Oumuamua, is really of extraterrestrial origin?

If it is it was poorly designed, visually speaking.  

Anything not formed on this earth is, by definition, extraterrestrial. So yes, by the letter of your question, it surely is. 
Do I think that it is a craft built by otherworld life forms? Probably not, but it’s too soon to negate the idea. 

To quote Hamlet: “There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.” This post was edited by Don Barzini at November 18, 2018 9:28 AM MST

First I better consult the latest issue of 'Scientific American'. 

Prepare for the big kaboom. 

have no idea

It's extra-terrestrial by definition, as Don Barzini says.

Whether it's natural or artificial is a totally different matter.

My guess is that it is simply a natural object among hundreds if not thousands in the Solar System, but it is so small (astronomically) and has such a far-flung, long-duration orbit it's not been previously been seen.