I can make this claim because Dejacque was the first to use the term to describe an ideology (here is the very first use [1], and here's a page on Dejacque's newspaper Le Libertaire[2]), and because when the term was introduced into right-wing anti-authoritarianism it was with explicit knowledge that it was co-opting the term as it had then been used for a century by the left.
Libertarianism as such was founded as a rejection of "moderate" anarchism, and a more extensive rejection of authority than that of Proudhon, along with an absolute rejection of property rights as oppressive.
That he was later adopted by some right-wing libertarians does not mean he invented libertarianism. Many people toyed with similar ideas. Dejacque was the person who gave it a name and promoted it as an explicit ideology.
You'll also not that Bastiat did not take things nearly as far as Dejacque did. E.g. Bastiat argued in Justice and Fraternity even for limited state provided welfare, so he did not even go as far as many right-libertarians. But whatever the size, he argues for a state, not the total dismantling of the state, which was the origin of libertarianism.
As such, Bastiat looks libertarian to right-libertarians because they took left-wing libertarianism and gutted the commitment to liberty of Dejacque to add in state restrictions on liberty to enable property, and in doing so shifted the ideology far to the right. But he's far less libertarian by its original definition than e.g. an anarchist like Proudhon. To left-libertarians he's just another statist.
Bastiat was a so-called right-wing libertarian in all but name only. Rothbard borrowed very liberally from Bastiat (no pun intended).
I don't recall reading anything like state provided welfare in Justice and Fraternity. It has been a very long time since I've read it, but that sounds antithetical to some of his other writings which I've re-read more recently. I would be curious to see the specific passage.
To my knowledge, communal arrangements (like Dejacque seemingly favors) have not proven practical outside of relatively small communities.
Libertarianism as such was founded as a rejection of "moderate" anarchism, and a more extensive rejection of authority than that of Proudhon, along with an absolute rejection of property rights as oppressive.
That he was later adopted by some right-wing libertarians does not mean he invented libertarianism. Many people toyed with similar ideas. Dejacque was the person who gave it a name and promoted it as an explicit ideology.
You'll also not that Bastiat did not take things nearly as far as Dejacque did. E.g. Bastiat argued in Justice and Fraternity even for limited state provided welfare, so he did not even go as far as many right-libertarians. But whatever the size, he argues for a state, not the total dismantling of the state, which was the origin of libertarianism.
As such, Bastiat looks libertarian to right-libertarians because they took left-wing libertarianism and gutted the commitment to liberty of Dejacque to add in state restrictions on liberty to enable property, and in doing so shifted the ideology far to the right. But he's far less libertarian by its original definition than e.g. an anarchist like Proudhon. To left-libertarians he's just another statist.
[1] https://theanarchistlibrary.org/library/joseph-dejacque-on-t...
[2] https://en.wikipedia.org/wiki/Le_Libertaire