>So what if that's some, very narrow definition of life?

It's not just some definition. It's the scientific definition. Lots of people have the motto "I believe in science" but then reject the scientific definition of life when it comes to humans.

>If I develop a tumor is it also a life? It certainly behaves so.

Well, we could survey those same biologists. I think they would say no. Does it have DNA of a unique person different from the person it's in? I'm not a biologist, but I think no.

>World is full of human life. West (and not only) manufactures failed wars that killed millions of civilians without a blink of an eye (Vietnam, Iraqs, Afghanistan just to name a few) and sends its own people to death. Where are those life-at-all-costs defenders?

https://www.solidarity-party.org/

Their 2020 presidential candidate is so life-at-all-costs that his website TLD is life: https://briancarroll.life .

>Such people are the last to force their own viewpoints on protecting life unto literally everybody else. Yet they feel the most righteous due to whatever fucked up morals they have to spread them and attack everybody who dares to think differently.

I'm not really sure what you're saying here. You say these people are the last to force their viewpoints on protecting life onto other people, but also they aggressively force their viewpoint on protecting life onto other people? That seems like a contradiction to me.