You're leading me nowhere because you aren't actually saying anything at all. Try actually answering questions if you want to lead someone somewhere.
> How do you define "value"?
At a basic level, usefulness.
> Is labor worth anything?
Yes, I value (it is useful to me) being able to leave my house without everything being overgrown. I value (it is useful to me) having the yard not overgrown to the point wildlife take over my yard and invade my home. I value (it is useful to me) to not have the trees overgrow above my roof and eventually lose limbs on to my roof. The way I achieve these useful things is by labor. So the labor is useful, it has value.
> How do you find out?
I look at the usefulness of that labor. What would it cost for me to hire exterminators once rats and snakes and bugs take over the yard and then my house? What would I have to trade for a doctor to heal me once I get sick from the rodent infestation? How would I repair my home after the damage from the infestations? What does a new roof cost if I don't maintain my trees? How much do I have to work to ensure these things don't happen? Then finally, given the fact I only have 24 hours in a day and I have other wants, is it useful to me to exchange something with someone else (something they find use of) to do it for me.
But going back to "is past labor less valuable than current labor", well, today do I care more about the lawn being mowed and the trees trimmed properly or do I just value that I did it six weeks ago and that's good enough for me now? In the end, today the trees are overgrown. The lawn is getting tall. Rats are starting to live in the bushes. I need to get out there now, despite the fact I did it six weeks ago. The value of that work I did then is now less, because the realities of the world continued changing.
A baker baked a loaf of bread a month ago. Is that labor still worth something today? Is that labor worth the same, more, or less than if he baked a loaf of bread today?
Try answering any of these questions next.