The Prophet pbuh said: “It is not permissible to shed the blood of a Muslim who bears witness that there is no god except Allah and that I am His Messenger, except in one of three cases: a soul for a soul (i.e., in the case of murder); a married man who commits adultery; and one who leaves his religion and splits form the jamaa’ah (main group of Muslims).” (Narrated by al-Bukhaari, 6878; Muslim, 1676)
If a Muslim apostatizes and meets the conditions of apostasy – example, he is of sound mind, an adult and does that of his own free will – then his blood may be shed with impunity. He is to be executed by the Muslim ruler or by his deputy – such as the qaadi or judge, and he is not to not be washed (after death, in preparation for burial), the funeral prayer is not to be offered for him and he is not to be buried with the Muslims.
Your answer is that Allah swt is the One Who revealed this religion and enjoined it. He is the One Who ruled that the one who enters it and then leaves it is to be executed. This ruling does not come from the Muslims’ ideas or suggestions. As this is the case, then we must follow the ruling of Allah so long as we are content to accept Him as our Lord and God.
You believing in these hadiths is because you worship men over God. No other reason.