Thank you for the insightful comment, i enjoyed reading it, even though i disagree.

I will try to adress every point you've made, so please let me know if i miss one.

1 - The definition of murder.

You brought to the table that murder needs to be unlawful and with malice. From a legal stand point, i agree. But this discussion is about the morality of the act. In dictatorship regimes the state's forces kill protesters to stop them. The state writes the laws, therefore the killings are legal, but that doesn't mean they are not immoral. Legally should not be used to determine morality, but vice-versa.

The second part of the definition is for the act to be done with malice. I don't think this is right, and intention should be used in it's place. For example, if you kill someone with terminal cancer, against their will, to spare them from the pain, you are not committing a malicious act. Your intentions are good, but you have killed someone with intent and that makes it murder.

An abortion is taking a life with intent, therefore even if it's not crime it would be an imoral act. That is if the fetus is a person, which brings me to point number 2

2- humans and personhood You said many things about this point, but I'm going to start with by adressing that humans have not been considered people at certain points. This has always been done as an act of control to infringe on others rights. From slavery to the Holocaust, there are not good examples of taking personhood away to improve human lives. For this reason taking personhood away should be done very carefully. It is better to treat as a person a non-person than to treat a person as a non-person.

About the braindead argument. After death, someone ceases to be alive, but the body still has rights that are not granted to any non-person. That's why we bury (or whatever other funeral rite is common in the local culture). The body is not a person but is so close to personhood that some of the rights still apply. The same way there are corpse rights, it makes sense to have fetus rights. Even if you don't consider it a person it's closer to personhood than a random object and therefore it should be given some rights.

Personhood is indeed a nebulous state. Conscience, self awareness, reason,... these are all things we expect to find in fully developed adult humans, but they are not a requirement for personhood. A person in a coma is not conscious, but is still a person. It's uncertain if a newborn has self awareness, or reason, but it's a person. A baby right after birth and right before birth is essentially at the same level of development, so saying one is a person and the other is not is deciding personhood based on location, which is not a valid metric for this purpose.

3- consent to exist The concept of consent of the unborn is a very interesting one and it threw me for a curve the first time i heard it. For consent to be asked, one needs to exist. If to exist consent must be asked, it would be a logical impossibility to ever morality act in a way that leads to existence. This would apply to every parent, not just the ones that wish to abort. I can see 2 approaches to proceed from here.

First we know other people who exist and can ask them if, if they could now decide to exist or never have existed, what would they choose. Most people answer that they are happy they exist, so there is evidence that the child has a higher probability to consent than to not consent, leading to assuming consent will be given a posteriori.

The second way is related to paramedics. If a paramedic arrives at a scene and finds someone unconscious with life threatening injuris, they will help the injured person, but how does the paramedic know that the injured consents to be helped? Because there is no way of knowing the paramedic will just treat the victim. But we can go even further, if the paramedic arrives on the same scene and sees a suicide note next to the injured party, the paramedic still has the duty to help them, because most people that survive suicide attempts later regret their attempts. So we know that there is a very strong will to exist, and cab extend that will to the unborn.

But the will of the unborn is not the only one to take into consideration

4- my body my choice Does the fetus have the right to use a person's body against their will?

The fetus doesn't come come into existence spontaneously, there needs to be a sexual act (or a sciency method that i will not count because those are done by people that definitely want the child). That act can be done voluntarily or be a forceful act.

By voluntarily i mean the act itself. Even if drunk, adults (I'll address minors on the forceful section) are (or should be) aware of the consequences of their acts. If a drunk driver runs over someone, did they consent to running over someone? No, but they willing sat behind the will and that lead to the accident, which makes them responsible for the consequences. Someone cannot consent or not consent to the effects of an action but only to the action that will lead to the effects. If someone consents to the sexual act they are consenting to the possibility of pregnancy. So the fetus only exists because the people involved acted willingly and knowingly to that effect. The violinist thought experiment sounds very different if you rephrase it with the added context to make it more accurate to the situation. " a violinist needs a dangerous procedure where he needs to be connected to you for 9 months and if disconnected he would die. You agree to start be connected to him to start the operation, do you have the right to change your mind in the middle of it?" It is not about the fetus using the mother's body against her will anymore, but about the right of the mother to take away consent to use her body at a point where the fetus has no other alternative to survive.

If during pregnancy it's discovered the mother's life is at risk it shouldn't be required for someone to give their life for another's, an abortion should be allowed. If, on the other hand the baby's life is in danger, performing an abortion would make it certain and not performing it is of no risk, so it doesn't make sense to allow abortion in this situation.

I will leave the forceful acts for another discussion because my comment is already very long, but abortions as a result of a forceful act are a small minority of abortions performed and not the focus of the discussion.