1. The real bitcoin came first, and there literally would be no BCH without bitcoin.
2. BTC is just starting to break into the mainstream and actually be used for things, BCH is not.
3. The symbol for bitcoin is BTC. That's the real bitcoin. The symbol for Bitcoin Cash is BCH.
all true but this is not how things work.
1. there is only one bitcoin that existed from the start. "came first" doesn't make sense in my opinion.
2. any other altcoin can and possibly will in the future enter mainstream but it won't make it bitcoin.
3. the symbol is platform specific, some call it XBT

the only important thing that makes bitcoin, bitcoin is the majority support. that is how it works in a decentralized network.
- the majority of hashing power aka miners
- the majority of nodes which represents people using bitcoin the right way
- the majority of services, businesses, merchants,...
we all decided this chain that we are using that now has Segregated Witness enabled is bitcoin so it is bitcoin.
- bitcoin cash didn't have the miner support so they had to create the incentive for them to come and mine it (difficulty manipulation and 1000+ blocks (12500 BCH/day) per day instead of 144 normal blocks/day)
- it didn't have the node support so they had to run a lot themselves on datacenters
- there is no merchants apart from bitcoin.com and the things they create. then some smaller ones here and there wanting to hype their business by adding multiple altcoins one of which is BCH