Why Why?

[Ferrocyanide]

Like asking why a wheel is a wheel.  Are you actually having trouble here?  Order and disorder are the underlying premises of the second law of thermodynamics.  

Yes, so calling a tree an ordered object, that is a convention.

The 2 nd law of thermodynamics does not deal with order. It deals with Entropy. In other words, it tells us about energy flow and how one type of energy converts to another and the reverse doesn’t happen. (There are some cases that are reversible).
For example, if a rock is at the top of the mountain, it has some Gravitational potential energy. It can role down the mountain, which means
Gravitational potential energy -> kinetic energy
kinetic energy -> heat and sound
sound -> heat

^^^^^That’s an example of a non reversible system.
I suppose you could state that the system goes from disorder -> order.

Another example is given here
https://www.grc.nasa.gov/WWW/k-12/airplane/thermo2.html

I'm responding to objections to purpose which round down to "that's just us inventing things because we fear death".  Well, sure, we do that, but that doesn't explain why (or how..if you prefer) it turns out that a lot of ideas about purpose lead to us willingly giving up our lives.

The question is, “Who says we have what purpose?”.
slartibartfast told us about

“My life doesn't have meaning otherwise
I won't feel fulfilled without having a purpose
I need to know what happens when I die”

My position is that the christian isn’t really talking about purpose(job, task, function). He doesn’t care about purpose at all. He is concerned about death.
In other words, that talk about purpose and meaning is smokescreen.

it turns out that a lot of ideas about purpose lead to us willingly giving up our lives.

How so?

Yeah, the convention of giving observations terms so that we can discuss what we see in specificity.   That there are many more actual and potential disordered states than ordered ones, and that some processes create local order while increasing global entropy.  Like our metabolism - which breaks down ordered things into disordered components to maintain our ordered cells...which is the difference between you being alive and human, and you being dead and compost.

Roger.

I suppose we could say that nature assigns a purpose, and if it did, a study of the animal could yield insight on that purpose

There is a difference between a purpose given to you by an intelligent being compared to purpose given by nature.
For example, I might write a program and run that program. The component that executes the program is the CPU.
Why do I write a program? Probably because I am going to get some use out of it.

Why do humans make hammers? Because they want to drive nails into wood.
Why do humans make watches? To synchronize events, to measure time.

CPUs, hammers, watches have a purpose.

A human has a brain and it thinks. It is a data processor and it forms ideas, solutions to problems.

Nature is brainless. It doesn’t take any decisions but there are designs in nature.
Something like a planet or star has a spherical shape since it is liquid or gas or plasma and there is the Gravitational potential energy -> kinetic -> sound + heat -> heat
So, you end up with spherical planets and stars.
So, the properties of matter/space/energy leads to certain designs.

For life forms, there are multiple options. You can be a brainless bacteria, a brainless phytoplakton, a brainful elephant.
However, there is competition taking place among them. If that bacteria cannot seek food and use it, it goes extinct since it will eventually get damaged or will run out of fuel.
These lifeforms need to have the right set of properties to survive.
If they don’t, then you end up with a lifeless planet.

But i think you already know those ^^^^^ things.

I certainly wasn't born with any feeling of purpose

I think most human babies have emotions. They feel hunger, they feel like pooping, they feel temperature and all that. Those basic functions help the baby survive.

Those are the “purposes” that nature has given human babies.

and on the other, I find it difficult to believe that people assign no more or less truth value to their own ideas about the purpose of their own life

Well, I can’t claim that what I described is the absolute truth.
It is hard to prove some of those things.
When it comes to people giving themselves a purpose, they use their emotions. They do what they feel like.