Portfolio Use of Photograph: Is it considered commercial use?

Let's make sure one thing is understood: Adobe Stock is not a "photography portfolio website." Absolutely not. And anything submitted to Adobe stock is a commercial use.

Incidentally: This question is not about stock and contributing to stock.

That's not proof that you can do it, but still, it is a good example of how to shoot people in more busy areas.

For your own site, you can do that, if you are careful enough, that other people are not recognizable. You do not have to care about IP troubles with logos etc. As you promote your photography, those are irrelevant as long as you do not sell your images with a stock agency. The reason Adobe and others want not to have logos and other recognizable items in the picture is, because of the broad use that stock assets could have.

And streets are public space, but still, you need to follow some rules. As you will do portrait, photographing wide open helps. And avoiding crowded places helps as well. Pictures in advertising that seem so causally to be street photos, are in reality highly staged.

The photos will be taken from the street so from public domain.

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Contrary to what you may think, street photos are NOT "in public domain."  Editorial content used for news reporting & journalism is one thing.  Commercial and/or promotional use is another.  

Copyright protection and privacy are no small matters.  Ask yourself if you can afford to be sued by any businesses or persons depicted in your photos.  This includes auto makers, street merchants or casual pedestrians who might recognize their likeness if they saw the photo.  When in doubt, consult an attorney for legal advice.  Or don't use the image for promotional purposes.

You could play it safe and shoot photos in remote places away from urban life. Or stick with studio photography.  But when you get into cities, you have to protect yourself with signed releases.