“There is only one really serious philosophical problem, and that is
suicide. Deciding whether or not life is worth living is to answer the
fundamental question in philosophy. All other questions follow from
-Camus, in The Myth of Sisyphus and Other Essays
I see Camus as saying, if you can't make the choice not to commit suicide, you will go into non-being with no other problems. So finding a reason to not die, is the first and primary problem, which preserves life to face any other problem. Perhaps you have to drink far too much coffee and spend all your time with people who wish they were revolutionaries but live under Nazi occupation, for this framing to seem obvious.
He also said in his semi-autobiography:
"He realized now that to be afraid of this death he was staring at
with animal terror meant to be afraid of life. Fear of dying justified
a limitless attachment to what is alive in man. And all those who had
not made the gestures necessary to live their lives, all those who
feared and exalted impotence— they were afraid of death because of the
sanction it gave to a life in which they had not been involved. They
had not lived enough, never having lived at all. And death was a kind
of gesture, forever withholding water from the traveler vainly seeking
to slake his thirst. But for the others, it was the fatal and tender
gesture that erases and denies, smiling at gratitude as at rebellion."
-Camus, in A Happy Death
This is reminiscent of Nietzsche on 'downgoers' as 'overgoers', that is that we need to go beyond fearing death or pain, to fully embrace life and joy.
For Camus suicide was an ever-present option, his bonds to life and to other people which might have drawn him back were minimal:
"Should I kill myself, or have a cup of coffee? But in the end one
needs more courage to live than to kill himself."
-Camus, also in A Happy Death
This can be related to Durkheim's book Suicide: A Study in Sociology, from which:
"Melancholy suicide. —This is connected with a general state of
extreme depression and exaggerated sadness, causing the patient no
longer to realize sanely the bonds which connect him with people and
things about him. Pleasures no longer attract"
He related anomie, the purposelessness that leads to suicide, to social decohesion and loss of connection to others. This is part not of our intellectual domain, but of our animal nature, which knows that without the tribe we are likely doomed. It is an intellectuals blindspot, to feel the suffering, but not recognise it's actual cause, and so see it as fundamental and inescapable, I think.