The Holy Quran is it only for Muslims or for All Human on Earth.?

Bismillah.

Dear friend, Al-Qur'an is for Muslims and humankind (mankind).

See these verses:

Surah 2:21

O mankind! Worship your Lord (Allah), Who created you and those who were before you so that you may become Al-Muttaqun

Surah 2:159

Lo! Those who hide the proofs and the guidance which We revealed, after We had made it clear to mankind in the Scripture: such are accursed of Allah and accursed of those who have the power to curse.

Surah 2:168

O mankind! Eat of that which is lawful and good on the earth, and follow not the footsteps of Shaitan (Satan). Verily, he is to you an open enemy.

Surah 2:185

The month of Ramadan in which was revealed the Quran, a guidance for mankind and clear proofs for the guidance and the criterion (between right and wrong). So whoever of you sights (the crescent on the first night of) the month (of Ramadan i.e. is present ...

Surah 22:1

O mankind! Fear your Lord and be dutiful to Him! Verily, the earthquake of the Hour (of Judgement) is a terrible thing.

Surah 22:5

O mankind! If you are in doubt about the Resurrection, then verily! We have created you (i.e. Adam) from dust, then from a Nutfah (mixed drops of male and female sexual discharge i.e. offspring of Adam), then from a clot (a piece of thick coagulated blood ...

Etc.

In Al-Qur'an. There are calls for mankind such as "Yaa ayuhannass" means "O..mankind (to the humans on this earth)".

For Muslims or the believers, Allah uses "Yaa ayyuhalladzii na aamanu" = "O you who believe! "

Other call, "Yaa banii israil" is the call special for the cildren of Israel.

Hope this answering your question.

Peace.