I wouldn't call it a bold hypothesis; its been generally affirmed through out history despite suffering that being human means, and of humanity in general.
Of course, the absolute worth of humanity in Europe had been under-pinned by Christian Theology; and whilst this continues, a break in morality has occurred as acknowledged by Arendt and others; and this moment is usually indexed by Nietzsche, though of course it had led something of an underground life till then.
Existentialism was one of the first fruit of this break - Sartre being its most prominent exponent; and also defending it from the charge that this philosophy would only, on the whole, lead to nihilism.
This is the question that Camus, for example, addresses this in one of his early writings: The myth of Sisphus. He starts by asking the question, does the absurd (the world without being grounded in God) require suicide? He answers:
"No. It requires revolt."
He acknowledges the life of the body as well as the thought that animates a man:
In a man’s attachment to life there is something stronger than all the ills in the world. The body’s judgment is as good as the mind’s and the body shrinks from annihilation
He then compares the absurdity of man's life with the situation of Sisyphus, a figure of Greek mythology who was condemned to repeat forever the same meaningless task of pushing a boulder up a mountain, only to see it roll down again.
He ends by:
"The struggle itself [...] is enough to fill a man's heart. One must imagine Sisyphus happy.
It is for this reason that Camus is usually taken as an Existentialist - though he himself repudiated the label; one need only recall, for example that his university dissertation was on St Augustine or his affinity to Simone Weil, a Christian/Jewish Mystic (and so exemplary in her suffering as to cause Susan Sontag to look away) to realise the simplicity of such judgements.
In the context of another tradition, Islam; jihad aligns itself with revolt in Camus sense; of course now it has a different sense of this word is much more publicly prominent; but then so does 'revolt' or rather 'revolution' in the Marxist tradition.