To me, it means Torah was while the Imams of guidance were there a perfect book with a perfect law. Then when Imams about to go hidden, because people rejected them, Jesus (a) has to annul some rituals meant for them and society to come to them through.
Islam is more of a compromise in all that. Since the ghayba could be long before Imam comes back and this was always to be prepared for as possible and it's universal not particular to a time and place, there was more of a pragmatic shariah for the world.
Moses' (a) and his code was particular to preparing for "the one who you will send" in his own words. Time and place changes needs of people and application of the light.
The light revealed by God is perfect for the time and place. Gospels were perfect to prepare people AFTER disappearance of Imams, and so were in principle less perfect, but more perfect for that temporary situation - and this was to be done by the church but only realizing that the Church is vulnerable and fallible and can go wrong.
Islam true perfection will only occur through Imam Mahdi (a), it's then his light is complete upon humanity when application of the Quran finally occurs and justice occurs and is not only talked about in theory but applied.
Quran doesn't give exact details of how much Zakat to pay, because perhaps, that changes over time. Perhaps are more justice becomes practically achievable and rights established, zakat amount changes. And it perhaps it was never universal, but even had brackets for richer to pay more then someone who needs the money or is not as rich.
There was also more dynamic approach, for example, you can separate your Salah in five times, or combine Dohr and Asr in either time and same with Maghrib and Isha. This was to keep things dynamically easy for believers.
Whatever they find more ease and peace in, they were allowed to practice.
The ultimate thing is God commands to justice and goodness, and said there is two ways to prove God enjoins something, by khabar (news) or by knowledge. Knowledge is a means - you can using reasoning with Quran and brings proofs indirectly, and narrate hadiths that reason properly. It doesn't have to be direct khabar.