For god's sake, nobody is saying that the first victim didn't matter.
As far as we know based on the limited information available, the first victim was stabbed in what was effectively a domestic dispute - he and the attacker were known to one another. Very sadly, this is not that unusual in this day and age, which is part of the reason why it has attracted less attention. At the risk of sounding callous and dismissive, which I don't mean to, a seriously mentally ill person attacking someone known to them is not uncommon enough to make national news, although it is of course very sad.
The other two victims were unknown to the attacker, they were attacked in broad daylight in a public place, and based on the information available to us, they were attacked because they were Jewish, in a place which is known to have a large Jewish population. That is unusual, far more unusual than the first scenario. It also needs to be placed in the context of an increase in attacks against Jewish people and the Jewish community - namely, the Manchester synagogue attack and the arson attacks on the community ambulance service (and many other smaller instances of anti-Semitism and harassment reported by British Jews).
The narrative you're trying to push is really disingenuous and unpleasant.