Put the words in context:
Gen2:9 And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.
The two trees were mentioned together with other plants in the Garden within one verse. So, it has to mean true plant.
I don't see why. You are making the mistake that an allegorical interpretation means every little detail has to have a symbolic meaning, it is certainly true that you get highly allegorical stories and highly allegorical interpretations especially in Medieval times where every single detail has a symbolic meaning, but that doesn't mean every allegory and parable has to work that way, what was the meaning of the pigs in the parable of the prodigal son, what about the husks that ate? Medieval allegorists did find meanings in them, but does that mean they were right or did they just take the parable too far? If there is not symbolic meaning in the pigs and the husks, does that mean the story isn't a parable? Actually the context of the parable is Jesus be criticised for eating with tax collectors and sinners, maybe the riotous living' of the prodigal is referencing real parties that the tax collectors and sinners threw. Does that mean the prodigal son is literal? Figurative language in the bible is much more creative and free than literalists realise.
If so, then the tree is not the "preincarnate Word". If the function of the tree of life implies God, then why would it use a figure like tree to represent it? I am sure there are better choices than a tree. For example, may be something like a living fountain (spring, river, etc.), or something similar to wind.
Water and wind is more often a symbol of the Holy Spirit, but Jesus referred to himself as a source of living water and a tree, as well as bread, door, shepherd, a road. John calls the preincarnate word, well, 'the word', John the baptist called him a lamb, Proverbs refers to him as a woman called Wisdom, Paul and Genesis refer to him as the seed.
There are so many different symbolic figures for Christ, you want to criticise Genesis for not picking what you think is the best one? Since Jesus was to die on a tree and it is by abiding in him that we bear fruit, and given that in Genesis the seed of the woman was to be bitten by the snake and crush its head, I think the choice of symbols in Genesis for the preincarnate word is very powerful since the reason for his incarnation, his death on the cross, was foreordained before the foundation of the world.
The power of giving life is from God. If God says eat that rock, or drink that water, and you will live forever, that does not mean the rock or the water needs to be God Himself.
Like I said, that gives you two source of everlasting life, God in Christ, and a fruit tree. It really undermines the uniqueness of Christ, which as I said is a theological problem. But I don't think a literal tree could be the source of everlasting life. John 6:27
Do not labour for the food that perishes, but for the food that endures to eternal life, which the Son of Man will give to you. For on him God the Father has set his seal. Fruit perishes when you eat it, as Jesus pointed out about food making people unclean, it goes into the stomach and is expelled. Literal fruit cannot give eternal life. It needs to be something spiritual. John 6:63
It is the Spirit who gives life; the flesh is of no avail. The words that I have spoken to you are spirit and life.
--------
A side question to Assyrian: Is there anything in Gen 1 to 3 you are willing to take literally? My guess is none. If so, your theology can work without these three chapters. Because all the metaphoric interpretations about these three chapters can also be made from later Books and chapters.
Does that make the bible fractal? Some people come to know Jesus simply through a single gospel. John was probably the only person in the in the New Testament who could have had a complete New Testament. We have four gospels, Jesus taught the same truths in multiple parables. The most important teachings are repeated again and again, in fact if a doctrine depends on a single passage it is probably suspect. 'Baptism for the dead' anyone? Personally I look for my creation accounts in Gen 1-3, Job 38, Psalm 104, Prov 8 and avidly read all the figurative and allegorical interpretations we get of these accounts, Psalm 90, Romans 5, 1Cor 15, Heb 3&4. Jesus taught his disciples how to interpret all the reference to himself throughout the OT. Luke 24:27
And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself. Where do you see references to Christ in the Genesis Creation accounts?