The Thief is Satan. His Spirit, and offspring[progeny] has been present on the earth from the Garden, and via Cain - His son. This is explained for the mature, in Matt.13, the Wheat and Tares; and John 8. Importance? Yes: we have a Commandment/Law to learn the parable of the Fig-Tree - which is about two people, Satan, and Events that took place in a Fig-Grove.
"Nothing new." That is because Satan and His Children are not creative; they are copiers. They continue to do the same things, over and over, because it works. Inside the cycles, patterns, are what we need to look at. Satan is rebellious against our CREATOR; and so was His Son Cain.
Cain's Children = Kenites[aka Tares] grew. They believe and practice Control or Destroy. John 10:10 The Thief, comes to steal, kill, and destroy. It is obvious what is being Controlled or Destroyed. They are "Bad Figs" and this is their time: look around. It is not racist to look. Lets examine John 10:10.
The Thief = an embezzler, pilferer, transferred also to false teachers, who do not care to instruct men, but abuse their confidence[con-men], for personal gain. Steal = taken by stealth. Kill = sacrifice or slaughter. Destroy = render useless, to perish, be lost, ruined, to put out of the way entirely, abolish, put an end to. * All definitions from the Strong's Concordance.*
Study the definitions and compare the leadership in place - behind the scenes; then look at their "fruit" = their work, walk, and production. Look at the debt/bondage, violence, war, and millions of babies aborted - daily.
One-world-ism has been the objective since the Garden: the objective of Satan, and The Thief; Rev.13:3.