I always was amazed by how disciplines which can give very different grades of accuracy (exact sciences in contrast to others which fails in its predictions more times than they are successful) can all be considered science by part of the people. So digging into this I've read that in a modern sense science requires empiricism and scientific method, and by part of the people in a broader interpretivist sense these properties aren't required. So my question is, was interpretivism, or antipositivism, always considered science by part of the people, or this conception came into play later on?
According to the Wiki article you've linked to, Antipositivism is a relatively new concept which Newton would never have heard of. The article also explains that it only really applies to Social Sciences, according to it's proponents.
Personally, I think it came about and is applied by who it's applied by because that can't, in fact, prove anything empirically and rigorously about their areas of science.
I kept looking information about this, and after some time (I'm posting this answer almost 3 years after the question) I found this.
Antipositivism is a theoretical stance of social sciences. In the other hand, the first use of the term "social science",
first appeared in the 1824 book An Inquiry into the Principles of the Distribution of Wealth Most Conducive to Human Happiness; applied to the Newly Proposed System of Voluntary Equality of Wealth by William Thompson (1775–1833)
So I guess we could say no, interpretivism wasnt always considered to be "scientific", since it was part of social disciplines, which werent considered social sciences until early XIX century.