The gift of eternal life through divine grace is a spiritual gift. Yet, it was originally presented to mankind in physical form as the fruit of the tree of life (Gn 2:9). Why would God feed his earthly image (humans) divine spiritual life through a material object?

Because our nature is both material and spiritual.

As knowledge is gained through the physical senses and brain to be abstracted by the spiritual intellect, so too it is fitting that divine life be imparted through the physical body to transform the spiritual soul. That’s why Christ instituted 7 sacraments as physical channels of His divine grace.

God wills that all be saved (1 Tm 2:4), and Christ, who is “Logos” (Jn 1:1), is perfectly reasonable in establishing how best mankind can access the grace that is necessary for salvation.