The question of the earliest Hebrew inscription is more complicated than it sounds.
For past posts on Khirbet Qeiyafa and its inscription, see here and links and here and links. For the Eshba'al inscription subsequently discovered there, see here and links. For posts on the Gezer Calendar, see here and links. For the Tel Zayit abecedary, see here and links. And for other very early Hebrew (?) inscriptions, see here (final paragraph) and links.
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