Those commands were the greatest given at that time. If those OT commands were sufficient, Jesus wouldn't have given us a New Commandment in John 13:34. But He did. It's interesting that in 1 John 3:23, we read,
"And THIS is His commandment: that we should believe on the name of His Son Jesus Christ and love one another, as He gave £us commandment.
This commandment swallows and replaces the previous "great" commandment.
I actually think that commandment falls within the two greatest commandments I mentioned previously. And by the way, Jesus said that the two I listed (love God with all your mind, etc and love others as yourself were the greatest....period.:
Mar 12:31 And the second [is] like, [namely] this, Thou shalt love thy neighbour as thyself. There is none other commandment greater than these.