The ancient Indians recognised the human body to be frail and prone to problems.

However, a consciousness pervades the human body and the nature of this was held to be of a different nature.

Krishna indicates the nature of this immanent self.

na jāyate mriyate vā kadāchin
nāyaṁ bhūtvā bhavitā vā na bhūyaḥ
ajo nityaḥ śhāśhvato ’yaṁ purāṇo
na hanyate hanyamāne śharīre

This can be roughly translated to:

The self is neither born, nor does it ever die; nor having once existed, does it ever cease to be. The soul is without birth, eternal, immortal, and ageless. It is not destroyed when the body is destroyed.

– Bhagavad Gita 2.20