Blood animal sacrifices are not mandatory for atonement. Review the plethora of passages revealing a repentant heart will do just fine. Understand the various forms of payment (ie animals, flour, jewelry, incense, etc.) when a temple in Jerusalem exists, is based on affordability, offense, or circumstance to teach the accidental violator a lesson so as to not repeat their violation. Our court system today is based on this concept. Moreover, human sacrifice has always been forbidden (see Leviticus 18:21, 20:3; Deuteronomy 12:29-32; 18:10; 2 Kings 3:27, 16:3, 17:17; 2 Chronicles 28:3, 33:6; Jeremiah 7:31; Psalm 106:35-38; Ezekiel 16:20-21 as some examples) AND no human can die for another’s sins (see Deuteronomy 24:16; Ezekiel 18:1-32; 33:12-20; Jeremiah 31:29-30; Psalm 49:7). In other words, Jesus didn’t die for your sins. All you need is repentance.
When the author of Hebrews uses Psalm 40 to make the reader think a human sacrifice (Jesus) was required for atonement, he changed out what the Psalm actually says. In other words, the author lied. Intentionally deceived and still deceives unsuspecting readers. As Ronald Reagan said, “Trust but verify.” Look this stuff up for yourself.