It is not enough to describe the living being within the body as simply being a ‘spirit’ – or as is stated in the Vedas ahaṁ brahmāsmi(I am spirit). We are also a person or puruṣa(purusha) in Sanskrit. A dead body is not a person – it is just a body or covering which the ‘person’ has left behind. The departure of the person from the body is what is called death. ‘You’ don’t die, but the body does. ‘You’ continue to live, but elsewhere.
Life is the symptom or sign of the presence of spirit. That ‘spirit’ is an energy but it is also importantly a ‘person’. The symptom of life indicates the presence of a spiritual person, a puruṣa(purusha). Depending on the type of body covering that spiritual person, their unique individual existence and personhood may be obvious or not so obvious, or not obvious at all.
Mantra meditation is the means to gain the appropriate vision to clearly see this reality. As is stated in the Bhagavad-gita 5.18:
विद्याविनयसम्पन्ने ब्रह्मणे गवि हस्तिनि ।
शुनि चैव श्वपाके च पण्डिताः सम दर्शिनः ॥१८॥
The humble sages, by virtue of true knowledge, see with equal vision a learned and gentle brahmana (a refined and elevated human being), a cow, an elephant, a dog and a dog-eater (a low person).