'Life is not simply in the blood of Biological beings. What if you remove the brain?'
The Bible needs to be understood in the context of those for whom it was originally written. Long before Harvey described blood circulation, long before anyone knew that every living cell requires a blood supply for survival, blood was thought to be 'the life principle'. That presumably arose because, by common observation, if a person lost enough blood, death ensued. It does not matter to us what the biological truth is, it is the perception of the first readers of the Pentateuch that matters.
But in any case, the purpose here is not to do with biological life, but the life of the 'eternal' spirit, for which biological life, and blood, form an analogy. Literal blood was to form a visual parable, its use in obtaining notional atonement for sins arising from, and giving rise to the precept that 'without the shedding of blood there is no forgiveness'. So when a later Bible author writes 'To him who loves us and has freed us from our sins by his blood,' it means that life, spiritual life, has become available to mankind because of the loss of spiritual life of the Christ, made manifest by the literal loss of blood of the crucifixion. That is why the blood of Jesus is spoken of as 'precious', and why superstitions about that blood subsequently arose. The significance of blood throughout the Bible is really that of the freeing of the conscience from guilt of sins committed, sins being offenses toward deity; and that end is the whole purpose of the Bible. This concept of forgiveness through blood has been called the 'red line' that starts in Genesis and continues unbroken to Revelation.
'It would surely help if people did that instead of looking at it through 21st century eyes.'
There will always be a faction or factions unable to resist doing so. For one thing, to treat the Bible as a science textbook subjects it to inapplicable criticism. For another, to make the basis of a belief system based on personal trust an intellectual one by itself makes it Christian only in name, lacking the motivation to effect personal moral change. Thirdly, the view of creation in six literal days with a day of rest supports a very part-time mock version of Christianity based on a 'sabbath' or 'Lord's day', which observance is inimical to Christianity.