The benefit the US gets from protecting Poland is that in doing so it helps keep Russia boxed in, it keeps great influence over the EU (Poland is a pivot of US influence on the EU), thereby greatly helping curtail 2 out of 3 threats to the US's position as the most powerful country on Earth. It's not done out of benevolence but it's quite great for Polish people.
That's, by the way, a result of a 12 year period, compared to the list you gave that's over 80 years.
Those aren't great lives by any means, but avoiding Iran-Iraq V2, or Turkish invasion of most of Syria, a complete Azerbaijani victory, or complete subservience to China, is genuinely a positive. On the greater balance, simply existing as a counterbalance to the US is something that's useful for most of the world, which explains indifférence over Ukraine.
Did the US want to annex that country into the US? And convert its citizens into obedient Americans? And murder everyone who resisted?