The success of Javascript is entirely due to there being only two languages in which you can program a web page with full control over client behavior: Javascript, or something that translates to Javascript.
It could never have survived on its own in the wild.
Javascript is not the first scripting language with C like syntax. Before Javascript there was LPC (C-like language for programming LPMud). https://en.wikipedia.org/wiki/LPMud
And of course the C-like language within Awk where you can write things like:
function add(a, b)
{
return a + b;
}
LPC was cloned by a GPL-ed language called Pike in the mid 1990's. You don't hear about LPC or Pike today. (Part of the reason for which is probably the rise of Java to prominence in the area of "managed languages that look like C"). Awk is around because it's part of POSIX. It's the only language other than the shell you can count on being there.
A Javascript developed as a project not connected to the web would likely receded into obscurity like Pike.