if you did not intend to kill someone, you lack the mens rea but may still be guilty of negligent homicide
The standard varies by jurisdiction, but it's quite common for "intended to cause non-lethal injury but accidentally killed the victim" to be treated as murder; this arises for example in the "eggshell skull rule".
Some states also have what is referred to as "constructive murder" whereby you can be convicted of murder if you commit a serious crime and someone dies, regardless of whether the possibility of a death was reasonably forseeable; in Canada this has been ruled unconstitutional on the grounds of lacking mens rea but in the USA courts generally accept that having the intent to commit a serious (but non-lethal) crime meets the requirement.
“For example, 20-year-old Florida resident Ryan Holle was convicted of first-degree murder for lending his car to a friend, who used the car in a burglary during which a murder was committed.”
The eggshell skull rule is from torts, not criminal law and it would be unconstitutional to apply it to criminal law. You're thinking of constructive murder, where the intent to commit a serious felony everyone to the intent to cause all foreseeable harms that the attempt could engender.
Different countries, different constitutions. In Canada, constructive murder was ruled unconstitutional; but if you intend to shoot someone in the leg (say, to stop them from pursuing you) the lack of intent to kill would not save you from a murder charge.
The standard varies by jurisdiction, but it's quite common for "intended to cause non-lethal injury but accidentally killed the victim" to be treated as murder; this arises for example in the "eggshell skull rule".
Some states also have what is referred to as "constructive murder" whereby you can be convicted of murder if you commit a serious crime and someone dies, regardless of whether the possibility of a death was reasonably forseeable; in Canada this has been ruled unconstitutional on the grounds of lacking mens rea but in the USA courts generally accept that having the intent to commit a serious (but non-lethal) crime meets the requirement.