It has often been said that the Aseres HaDibros seem to be evenly divided between those that deal with our relationship to Hashem and those that focus on our relationship with our fellow man. When Moshe Rabbeinu came down with these commandments written on the Luchos, five on each Tablet, the laws were balanced between his two hands, one hand presenting religious doctrine and the other hand human ethics. The one Dibbur that doesn’t seem to fit is the fifth, Kibbud Av Ve’eim, which ends the first Luach, but seems to belong with the second group, the one that deals with inter-human relationships.
Indeed, the Ramban here says that there are only four in the "relationship with Hashem" group, and Kibbud begins the six that involve our relationship with our fellow man. He adds that kibbud is listed first in the second group because it relates to the first of the first group, Anochi. Honor your father as you honor Me, because I am your heavenly Father, and he is your earthly father. True, he later says that the luchos were equally divided between man/G-d and man/man, because we honor our parents because they are Hashem's partners, and just as we honor Hashem, we ought to honor His partners, so it is also man/G-d. The connection seems tenuous, dachuk, in light of his earlier statement that Kibbud is man/man. In any case, although the Ramban’s explanation does connect Kibbud to Anochi, it would be nice to understand why Kibbud is so closely related to the others that are on the same Luach, those that are בין אדם למקום, between man and Hashem.
This Kli Yakar would also explain what Kibbud is doing on the first luach. This deep connection between Kibbud and Shabbos results in every mention of Kibbud being immediately followed by Shabbos, and because of that connection they had to be on the same luach.
But does that mean that the idea that the first luach instructs us about בין אדם למקום, man to G-d, and the second about בין אדם לחבירו, man to man, is not correct?
In short: Why is כיבוד אב ואם on the first luach, which otherwise focuses on בין אדם למקום, and not on the second, which deals with בין אדם לחבירו? Because the first five are not בין אדם למקום, they are בין אדם ליוצרו.
ויפקח א־לקים את עיניה. — א״ר בנימין חכל בחזקת סומין עד שהקב״ה מאיר את עיניהם, שנאמר: ויפקח א־לקים את עיניה. (ב״ר נ״ג) ג.