[AutocadOemM]

Out of curiosity, how do Muslims reconcile the fact that everything blessed is located in Arabia?

God sent this prophet to Arabia,

The Prophet was indeed sent to Arabia but He was not the Prophet of Arabia . He was sent for the whole of mankind. His message has crossed Arabia and spread to all corners of the world

speaking Arabic,

The language is blessed for the Muslims. The Non Muslims are devoid of the language's blessings. The Qur'an is in Arabic and it is a blessing and cure Not for the Arabs but for the Muslims

praying to this Qibla in Arabia,

Again the Qibla is a blessing for the Muslims. The Kaaba is the first House of Allah on this Earth. It is blessed by Allah and not because it is in Arabia

traditional Arab medicine (hijama) is recommended,

Even Greek, Indian and Modern medicine is recommended

Arabian water (zamzam) is blessed,

The 'Arabian' water ZAM ZAM is again a blessing for Muslims, Arabs & Non-Arabs alike. It is not permissible to give ZAM ZAM to a Non Muslim. Allah 's blessings are for the Believers

Hajj pilgrimage is to Arabia, etc.

same as above

Certainly if the world is created by God and is so large, why isn't anything blessed located in, for example, South America or China? Why is the final religion so Arab-centric?

The Final Religion is Allah-centric.

I am honeslty looking for an answer. I was very very close to saying my Shahadah (even started praying regularly before) but I backed out only because I couldn't get an answer to this question to my satisfaction.

-Jason

May Allah guide you to Islam