Basically I would be given X shares for my work and with the current number of stock that came out to 1% of the total stock, BUT as investors come on this percentage will decrease.
Does this mean that more stock can be created?
Yes. In fact, that is precisely what happens in subsequent rounds of investment.
Could the company just create a billion more shares and render mine essentially worthless?
Yes. Protecting against the majority shareholders creating more new shares
and awarding these shares to themselves is usually done in a Shareholder's Agreement, or sometimes the company bylaws, or sometimes provisions buried somewhere else in all the legal paperwork. If you don't have a clause somewhere which clearly protects against this issue, then you're at some risk of it happening.
There is IMHO a meme going around about "non-diluteable shares". There is no such thing, it's a false meme propagated by a certain movie. You can have a non-dilution clause somewhere, but be aware that this can be highly disadvantageous for new investors, and can mean you outright loose access to vital outside investment.