Interesting chapter. I dont think he literally meant son. There's obviously some kind of familial connection there. My dads an asshole, and his brother looked after my and my brother at our lowest point, he calls the both of us 'son'. He's prolly saying that in such a cryptic way so that ichigo's curiosity will be peaked and he'll go to JB for information.
And for all the people crying about ichigo getting stronger - it's a fucking shounen battle manga. Did you expect him to get weaker? Stay the same level of strength? The point of the manga is to obviously fight stronger and stronger opponents. If he could beat them at his current level of strength, THAT would make him overpowered. Not the fact he's a chimera and keeps powering up. We were never explicitly told EXACTLY what ichigo is, things have just been implied by other character. (And ill say it again, just because a character says something does NOT NECESSARILY MAKE IT TRUE, even if they say it with 100% confidence) therefore, his origins are still up for explanation, allowing kubo to do whatever the fuck he wants with it until it's set in stone.
For all the people comparing to StarWars, i have one thing to say - wait and see what happens before you jump the gun. Its ONE chapter out of 514. ITs the START of the arc. He's setting all these things up for the chapters coming out over the NEXT TWO YEARS. Stop being so impatient, stop turning implications into for sures, and wait and see.
When you're reading a novel, do you get the shits after 2 pages because it doesnt suit what you think it should be? No. You read because the author has decided the story, even if you have to wait till the last page to find out what the big secret is.