I enjoyed creating the last 'what am I' and came up with another. (The title also fits the answer).
I often create barriers that can be broken.
I started as waves but was eventually scratched in stone.
Now there are thousands of us, none exactly alike.
What am I?
Slight Hint:
Communication is key, yet I cannot speak.
You are:
Language
(Title) Everyone has and knows one
We all have a native language. Some of us have/know more, but we all know at least our native tongue.
I often create barriers that can be broken.
Language barriers
I started as waves but was eventually scratched in stone.
Language was first oral only, then was finally committed to written form - scratched into stone
Now there are thousands of us, none exactly alike.
There are lots and lots of languages, natural and artificial
(Hint)
Communication is key, yet I cannot speak.
Language is all about communication, but language itself does not speak, it is (perhaps) spoken.
Possible answer;
Sand
I often create barriers that can be broken.
Sand in streams will often build up and make mini dams, (That can easily be destroyed.)
I started as waves but was eventually scratched in stone.
Sand is in the ocean waves, but then can get washed onto the shore and become sedimentary stones.
Now there are thousands of us, none exactly alike.
there is a lot of sand but each grain is different.
Unsure about this answer, but I suspect that you are
Written Law(s)
I often create barriers that can be broken.
A law or regulation places boundaries that limit what people can or cannot do. However, it is possible to disobey and violate these laws.
I started as waves but was eventually scratched in stone.
Originally, people followed oral law that was created and carried on via speech, which consists of sound waves. Once writing was developed, people began to carve the laws in stone (example: Hammurabi Code).
Now there are thousands of us, none exactly alike.
Each nation or civilization has a set of laws. Because the nations are distinct, these sets of laws are specific to individual nations, and are thus unique.
(Hint)
Communication is key, yet I cannot speak.
Laws are written in order to preserve them over time, so that they can be communicated between people in different societies. The written laws, being literal text, are unable to speak.
Although I don't know if this really fits the question's title.
Ok, this is a little silly, but it works. You are:
A personal relationship with God (i.e. YWHW)
(Title) Everyone has and knows one:
From the perspective of the Catholic Church, and most major Christian groups, this is the case. c.f. for example Gaudium et Spes section 1 chapter 1 subsections 14-19
I often create barriers that can be broken.
There's an idea that God tests people and stuff. Like, the book of Job but also in Paul's epistles he talks about ways that a relationship with God necessarily causes you to encounter problems but also you can overcome those problems.
I started as waves but was eventually scratched in stone.
"In the beginning God created the heavens and the earth. Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters." So our first relationship between God and the world besides creating is hovering over the waters, which is kind of wave like. Or, better: "And God said, 'Let there be light,' and there was light. God saw that the light was good, and he separated the light from the darkness." --the other traditional 'first' thing God does, and we all know light is a wave (sometimes), so that works too. 'Scratched in stone' works really well also-- we later get the 10 commandments, which are represented as etchings on stone tablets, and form the basis for a different sort of personal relationship with God (as shown by e.g. John 14:15 "If you love me, keep my commandments"). So that's pretty cool.
Now there are thousands of us, none exactly alike.
Well, billions is more than thousands, but it's the same idea. Everyone has their own relationship with the divine, and they're all different.
(Hint)
Communication is key, yet I cannot speak.
Prayer. I mean, 'cannot' is a little strong, but I think burning bush situations aren't exactly common
I know it's not what you were going for, but it fits really well and I think that's really amusing, so there you go ;P
