This essay by Tom Rockmore may be of some help in showing the way that the French interpreted Heidegger in the 1930s and 1940s. They (mis) interpreted Heidegger as a humanist.

I have not been able to find Heideger's Letter on Humanism online. In its absence we can work with this article by Daniela Neu,, since it offers a more philosophical interpretation. Daniela says:

"In the Letter on Humanism, Heidegger claims that we need to think the relation between Being and humans more originally than metaphysics. But this requires also a language which is no longer indebted to metaphysics. The problem in speaking of the relation between Being and humans or, as Heidegger states it in the Letter on Humanism, of the relation of Being to humans is that our traditional language invites us to conceive humans and Being as two separate entities, the relation of which is in question. Our traditional language is the language of metaphysics, and more specifically of modern metaphysics, for which the object of thinking is that which the thinking subject represents to itself."

The task of philosophy is to help bring back humans and beings in general to the place which they originally belong, i.e., to their most fulfilled way of being which is their proper or own [das Eigene, eigen]. The term "En-own-ment" or "Ap-propri-ation" [Er-eign-is] — the key word in Heidegger's thinking since the 1930's — marks his attempt to think more originally than metaphysics the relation between Being and humans in terms of the being "enowned" of humans through Being and in terms of the belonging of humans to Being.